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天然错断的花岗片麻岩的显微构造观测表明,在325℃以下和小于8—10km的深度内,长石颗粒比石英颗粒容易破裂。长石颗粒主要以晶粒断裂、沿节理控制的裂隙滑动和碎裂形式变形。断裂带中长百颗粒的裂隙促使它们蚀变成为高岭石。石英颗粒也以破裂形式变形,且在粉碎了的长石和高岭石的基质中,它们常愈合成石英碎斑和镶嵌结构。长石颗粒的同构造蚀变作用可能弱化了断裂带并导致形成了断裂带中的叶理构造。天然变形岩石的这种研究确证了在低温低压下对花岗质岩石变形行为已有的实验结果,而且所有这些资料表明10km以上地壳的流变学在很大程度上受到长石的碎裂作用影响。
Microstructural observations of naturally faulty granitic gneiss show that feldspar grains are more susceptible to cracking than quartz grains below 325 [deg.] C. and less than 8-10 km. Feldspar grains deform mainly in the form of grain fractures, sliding and fracturing along joint-controlled fractures. Cracks in the long strip of particles in the fault zone cause them to change into kaolinite. Quartz grains also deform in rupture, and in the matrix of crushed feldspar and kaolinite, they often coalesce into quartz crinkles and inlaid structures. Isomorphic alteration of feldspar grains may weaken the fault zone and lead to the formation of foliation in the fault zone. This study of natural deformation rocks confirms experimental results of deformation behavior of granitic rocks at low temperatures and pressures and all of these data suggest that the rheology of the crust above 10 km is largely affected by feldspar fracturing influences.